The present invention relates to a flow pump, particularly to a flow pump for feeding fuel from a fuel tank of a motor vehicle and, more particularly, to a flow pump of a type that includes a pump housing provided with a pump chamber having two radially-extending side walls axially spaced from each other and connected with each other by a peripheral wall, the two radially-extending side walls being provided with respective groove-like side channels open to the pump chamber and concentric with the pump axis, and a rotatable impeller arranged in the pump chamber and comprising circumferentially spaced radial impeller blades bounding axially open impeller chambers and an outer ring connecting the impeller blades with each other, a radial space being provided between the outer ring and the peripheral wall.
A double-flow flow pump of this kind, which is called a peripheral pump, is described in German Patent Application DE 40 20 521 A1. This double-flow flow pump has a pump chamber bounded by several walls including a side wall and a peripheral wall which are part of an intermediate housing having a pump outlet in it and another side wall which is part of a housing cover having a pump inlet connected with an inlet connector. The impeller arranged in the pump chamber is mounted on a bearing pin on the housing cover and is nonrotatably connected with the drive shaft of an electric motor, which is located in an assembled configuration in the intermediate housing. During operation the flow pump draws fuel in via an inlet connector and forces it through the pump outlet into the pump housing surrounding the interior space of an electric motor and the intermediate housing. The fuel is supplied under pressure through a high pressure pipe to a high pressure connection of the pump housing to the internal combustion engine.
A relatively large radial space exists in this flow pump between the impeller outer periphery and the peripheral wall of the pump chamber so that a convective input of dirt particles into this radial space occurs because of the pressure conditions during feeding of dirt-laden fuel. As a result, comparatively rapid wear and reduced lifetime of the pump occurs.